The invention relates to a communication system, method and processing means for switching calls via a transmission network provided between two local networks. The telephone call is initiated by a subscriber of a first local network (e.g. in Dxc3xcsseldorf) and transferred from the first local network to a remote transmission network which then switches the call to a second local network (e.g. in Munich) which then transfers the call to the target subscriber. In contrast to the local network, which is in direct contact with the subscriber and provides a service (e.g. invoicing, maintenance etc.) for him, the remote transmission network merely has the passive task of rapid switching, usually without directly accessing the two subscribers of the local networks.
The invention particularly relates to the problem of how the remote transmission network can be brought out of this purely passive state and be directly connected to the subscriber, without relying on information from the local networks.
The invention was entailed by the following considerations. In the past, the local networks as well as the transmission network were strictly and centrally managed by the same system operator, e.g. by the German Post Office. This has drastically changed, however, over recent years as a result of opening up this market for private bidders. Now it is also possible for the individual networks to be operated by different private bidders. In particular, various remote transmission networks are available too. If a new supplier wishes to launch the new remote transmission network on the market, the principal problem is always of course to entice new customers and to get them to use the new network based on attractive offers. Although this does in principle apply to the local network operators as well, such operators are able to contact new customers or subscribers directly in order to provide them with a service.
New suppliers of remote transmission networks are, however, faced with the problem of being dependent on information from the local network operators because they do not have any direct access to the subscribers. As shall be explained below, every call transferred from the local network does in fact receive an identification (a transmission network selection parameter) that the specific remote transmission network is supposed to be selected, but at the time of call initiation, the remote transmission network operator does not know which type of subscriber is calling, i.e. whether the subscriber himself or the local network has selected the specific remote transmission network.
The problems as to why the remote transmission network currently does not exhibit any access, particularly on-line access, to the local network subscribers will be described below with reference to the prior-art communication system shown in FIG. 11.
FIG. 11 shows a first local network LN1 (e.g. Deutsche Telekom), a second local network LN2 (e.g. likewise Deutsche Telekom) and two remote transmission networks FN1, FN2 for selecting the subscriber or the local network. FIG. 11 shows the case in which the call is executed from subscriber A to subscriber B via the remote transmission network FN1, while a call by subscriber B to subscriber A is performed via the other remote transmission network FN2. The individual exchanges EX (e.g. just one EX is depicted in each network, although several EX may of course be provided) switch the individual calls within the networks, with standard signaling being performed between the networks using standard protocols (e.g. ETSI ISUP Version 2 (ISDN User Part) for the SIGNALLING SYSTEM No. 7, described in ITU-T Recommendation Q.763). In the communication system in FIG. 11, there are in principle two possible ways of selecting one of the remote transmission networks FN1, FN2, viz. xe2x80x9cby contractual preselectionxe2x80x9d and xe2x80x9cby subscriber selectionxe2x80x9d.
Transmission Network Selection by Contractual Preselection
As shown by the hatched line between A⇄FN1, subscriber A has made direct contact with the remote transmission network 1 and concluded an exclusive contract with this transmission network. Subscriber A or the remote transmission network 1 notifies this to the operator of local network LN1 so that all the calls initiated by subscriber A are directed via FN1. If subscriber A dials the desired national telephone number NDC of target subscriber B, the local network then looks up in a local memory 1-1 whether a specific preselection for the remote transmission network was made on behalf of subscriber A. In this instance, memory 1-1 indicates that FN1 is to be used. The local network together with a call set-up parameter block NDC, CSP1, CLI transfers the call set-up request to the remote transmission network 1. In other words, the local network adds a prefix CSP1 to the national telephone number NDC, whereby CSP1 is the transmission network selection parameter envisaged for FN1. A call line identification parameter CLI identifying the subscriber station or subscriber from whom the call set-up request originates is also transferred by the local network. Since the remote transmission network FN1 already contains information on subscriber A in an intelligent device IN for concluded contracts, it can identify subscriber A when a so-called black-and-white checking test is performed using a corresponding REG content. If a match exists, the remote transmission network FN1 is able to transmit the bill for the exchange directly to the subscriber.
Transmission Network Selection by Subscriber Selection
In contrast thereto, subscriber B deliberately chooses the remote transmission network FN2 during call initiation, whereas he has not previously concluded any contract with this network. Subscriber B himself inputs a preselection by means of the transmission network selection parameter CSP2 together with the national telephone number NDC so that the local network LN2 knows that the call from subscriber B has to be directed after FN2. Like the FN1 network, the remote transmission network FN2 also receives in this instance a call set-up parameter block consisting of NDS, CSP2, CLI. The remote transmission network FN2 does not, however, find any kind of entry whatsoever in its intelligent device IN, because a contract with subscriber B does not yet exist. In this case, FN2 has to transfer the bills for settlement of accounts to the local network LN2 and does not have any direct access to subscriber B whatsoever. In other words, in instances where the standard transmission network selection parameter CSP is overwritten by a parameter CSP2 set by the subscriber, the operator of the local network LN2 and the operator of the remote transmission network FN2 have to have reached contractual agreements.
This approach is not especially advantageous because a new operator of a new remote transmission network therefore always relies on cooperation with the local network operator. The only option available to the remote transmission network operator is simply not to permit the call, which is in turn far from beneficial since the remote network operator is after all dependent on customers. The only active intervention is therefore restricted to the black-and-white checking test shown in FIG. 12.
Black-and-white Checking Test
In step S1, the remote transmission network FN1, FN2 reads the call line identification parameter CLI and decides in step S2 whether a test is to be performed using a black list or a white list. The black list contains entries about subscribers on whose behalf a contract has been concluded, whereas the black list contains entries for subscribers who have not concluded a contract. The left and right branches in FIG. 12 are therefore analog.
If a corresponding entry indicating that a contract has been reached with a subscriber is found in step S3 or S4, the call can be switched and processed (steps S5, S6). If no corresponding entry is found, the only solution available in the prior art is to release the call (steps S5, S6). As already mentioned, merely releasing the call is not a good way of economically operating the remote transmission network, thus leaving the operator no choice but to be compelled to process this call instead of releasing it and then to use the local networks to enter into contractual processing. But this is extremely restrictive and limits flexibility on a fiercely competitive market.
In conventional terms, the remote transmission network""s active option of decision making therefore did not go beyond a simple YES/NO decision about these fundamental types of call (call with a transmission network selection xe2x80x9cby contractual preselectionxe2x80x9d or xe2x80x9cby subscriber selectionxe2x80x9d). In principle it was indeed feasible for the remote transmission network operator to contact the local network operator at predetermined periods of time (e.g. once a month), possibly in order to obtain information on any subscribers already negotiated. Once again, however, he is dependent on the local network operator""s assistance and in particular he does not receive any on-line information, i.e. exactly when the call is being set up.
As already described in relation to FIG. 11, standard protocols such as ISUP are used between the remote transmission network and the local network. The addition of the CSP parameter has already been discussed in the xe2x80x9cSignaling for Interconnectionxe2x80x9d national working group for the German market; this parameter is based on the Transit Network Selection parameter TSN described in ITU-T Recommendation Q.763 (see also specification xe2x80x9ccarrier selectionxe2x80x9d; interface specification xe2x80x9cSignaling in ZZN7xe2x80x9d; version 1.1.0; ITU-T Q.763 xe2x80x9cFormat and Codes of the ISDN User Part).
In order for the remote transmission network operator to receive information on whether the remote transmission network xe2x80x9cby subscriber selectionxe2x80x9d (xe2x80x9ccall-by-call selectionxe2x80x9d) or xe2x80x9cby contractual preselectionxe2x80x9d (xe2x80x9cpreselectionxe2x80x9d) was chosen, the current proposal is to extend the CSP parameter so that it contains information on the type of selection, i.e. about how to go about selecting the remote transmission network.
But the problem is that a standardized ETSI ISUP version 2 used between the remote transmission networks and national networks has to be modified by a special parameter for national use. All the system operators working on the German market must therefore implement this parameter and every local network operator has to store in a memory the parameter""s contents for each subscriber belonging to this network.
Yet altering the national protocols requires the consent of the exchange systems suppliers and entails changing the signaling at the exchange systems, which cannot be performed in a short time or without considerable outlay. Since alterations also have to be performed in a highly sensitive area, namely switching center call control or the protocol, it cannot be expected that well-established national protocols will be altered in the near future simply at the request of the remote network operators.
As far as the remote network operator is concerned, the aforementioned disadvantages consequently remain, viz. that he is dependent on the local network operators"" cooperation in order to ascertain whether new subscribers would like to test out the new remote transmission network even without a contract, for example on a trial basis,.
The invention""s object is therefore to provide a communication system, method and processing means within a remote transmission network which enable the remote transmission network operator to ascertain information on the type of call without altering the interface protocols and without being dependent on the local network operators"" assistance.
The Object""s Solution
This object is solved by a communication system for switching calls between a first subscriber station of a first local network and a second subscriber station of a second local network via at least one transmission network provided between the local networks and comprising at least one switching center connected to the first and second local networks, with the at least one switching center receiving a call set-up parameter block with at least one call line identification parameter every time there is a subscriber station call set-up request from the respective local network; this parameter identifies the subscriber station from which the call set-up request originates, with the transmission network comprising at least one special service provider connected to the at least one switching center
for receiving at least the call line identification parameter of the call set-up parameter block from the switching center when there is a subscriber station call set-up request; and
for performing special services for the subscriber station making the call in accordance with the received call line identification parameter.
This object is also solved by a method of switching calls between a first subscriber station of a first local network and a second subscriber station of a second local network via at least one transmission network provided between the local networks and comprising at least one switching center connected to the first and second local networks, with the at least one switching center receiving a call set-up parameter block with at least one call line identification parameter each time there is a subscriber station call set-up request from the respective local network; this parameter identifies the subscriber station from which the call set-up request originates, whereby a special service provider connected to the at least one switching center of the transmission network
receives at least the call line identification parameter of the call set-up parameter block from the switching center when there is a subscriber station call set-up request; and
special services are performed for the subscriber station making the call in accordance with the received call line identification parameter.
The object is also solved by processing means in a transmission network for switching calls between a first subscriber station of a first local network and a second subscriber station of a second local network having at least one switching center for a connection with the first and second local networks, whereby each time there is a subscriber station call set-up request from the respective local network, the switching center receives a call set-up parameter block with at least one call line identification parameter that identifies the subscriber station from which the call set-up request originates, with the processing device comprising a special service provider connected to the at least one switching center
for receiving at least the call line identification parameter of the call set-up parameter block from the switching center when there is a subscriber station call set-up request; and
for performing special services for the subscriber station making the call in accordance with the received call line identification parameter.
The object is also solved respectively by each of the claims 34-41. According to the invention, the transmission network comprises a special service provider which performs special services when there is a call set-up request instead of YES/NO test, as described above, in accordance with the received call line identification parameter CLI. These special services may for example be active functions or programs that also make it possible to handle subscribers who have not yet concluded a contract with the network operator. The remote network""s function is therefore no longer exclusively limited to the passive exchange of calls, but an active intervention in the call that is taking place can even be performed. By consequently having functions or programs performed in the remote transmission network itself, viz. Merely in accordance with the call line identification parameter CLI (which is in any case transferred by the standard protocols), it is no longer necessary to cooperate with the local networks.
To perform special services efficiently, the special service provider may comprise memory means in which a specific special service parameter block is stored for each subscriber of a local network connected to the remote transmission network. This parameter block may be a set of standard special service parameters that is set once a contract has been concluded, or a parameter block which was updated or set for the first time during a renewed call (also in dialog with the subscriber). As soon as a subscriber may wish to test out the remote transmission network just for initial test purposes, the remote transmission network is therefore immediately able to store a parameter block which can then be successively updated when the same subscriber makes renewed calls. The remote transmission network therefore operates self-sufficiently without being dependent on the assistance of the local network operators.
The following are examples of special services that can be performed as programs or functions on the basis of the special service parameter blocks: forwarding a message, advertising or music to the subscriber placing a call; controlling a calculation of fees; performing a bidirectional on-line dialog with the subscriber placing a call; sending information material to the subscriber making a call; limiting the call time; interrupting the call at predetermined intervals of time in order to play advertising/messages or music during the breaks; forwarding bills or application forms to the subscriber making a call; producing statistics; producing itemizations of calls made via the transmission network; controlling the transmission network""s transmission speed for the call to be performed; automatically calling back the subscriber at predetermined intervals of time; and forwarding messages to the subscriber who has been called.
In relation to the communication system, method and processing means, it is advantageous for the transmission network to comprise at least two gateway switching centers each connected to the first and second local networks, for the gateway switching centers to receive the call set-up parameter block and for the special service provider to be connected to the gateway switching centers and to receive the call set-up parameter block when there is a call set-up request from one of the gateway switching centers.
In relation to the communication system, method and processing means, it is advantageous for the call set-up parameter block to comprise, in addition to the call line identification parameter, a transmission network selection parameter, whereby the switching center determines on the basis of the transmission network selection parameter whether the transmission network is selected for exchanging the call.
In relation to the communication system, method and processing means, it is advantageous for the local network to select a transmission network envisaged for transmission of the call initiated by the subscriber station and composed of a plurality of transmission networks in accordance with a concluded contract between the subscriber station and the transmission network operator, and to set the transmission network selection parameter correspondingly (transmission network selection by contractual selection).
In relation to the communication system, method and processing means, it is advantageous for the subscriber himself to select a transmission network envisaged for transmission of the call initiated by the subscriber station and composed of a plurality of transmission networks, and to set the transmission network selection parameter correspondingly (transmission network selection by subscriber selection).
In relation to the communication system, method and processing means, it is advantageous for the switching center to comprise means in which are first stored call line identification parameters that identify specific subscribers and/or subscriber stations whose calls are permitted for transfer via the transmission network by contract between the transmission network operator and the subscriber and/or subscriber station and, when there is a call set-up request, for the switching station to compare the received call line identification parameter with the stored call line identification parameter and to permit the call to be set up or exchanged when a match is established (calls with transmission network selection by contractual preselection) and to block it when no match is established (call with transmission network selection by subscriber selection).
In relation to the communication system, method and processing means, it is advantageous for the switching center to transmit the call set-up parameter block to a special service control device of the special service provider which comprises memory means in which call line identification parameters are first stored that identify specific subscribers and/or subscriber stations whose calls are permitted for transfer via the transmission network by contract between the transmission network operator and the subscriber and/or the subscriber station (calls with transmission network selection by contractual preselection) and, when there is a call set-up request, for the special service control means to compare the received call line identification parameter with the stored call line identification parameters and to perform special services during a call set-up when no match is established (call with transmission network selection by subscriber selection).
In relation to the communication system, method and processing means, it is also advantageous for the special service control means to perform special services during call set-up when a match is established (call with transmission network selection by contractual preselection).
In relation to the communication system, method and processing means, it is advantageous for the special service provider to comprise memory means in which a special service parameter block (1, 2, x, z) is stored for each call line identification parameter, indicating the special services to be performed for a subscriber and/or subscriber station exhibiting the respective call line identification parameters.
In relation to the communication system, method and processing means, it is advantageousxe2x80x94with regard to subscribers and/or subscriber stations who conclude a contract directly with the transmission network operatorxe2x80x94for the special service control device, on conclusion of a contract, to select one of several standard special service parameter blocks and to store it in the memory means as the associated special service parameter block for the respective call line identification parameter, whereby on reception of the associated call line identification parameter, the special service control means performs the special services indicated by this special service parameter block.
In relation to the communication system, method and processing means, it is advantageous for the special service control meansxe2x80x94when it does not establish any matchxe2x80x94to select one of several standard special service parameter blocks, to perform the special services indicated therein and then to store this or another standard special service parameter block as a special service parameter block together with the associated call line identification parameter in the memory means.
In relation to the communication system, method and processing means, it is advantageous for the special service control means to update the parameters in the special service parameter block on reception of the associated call line identification parameter and/or to assign a new special service parameter block to the call line identification parameter.
In relation to the communication system, method and processing means, it is advantageous for the special service control means to update the existing special service parameter block or to re-assign a new such parameter block by means of data communication means which performs interactive communication with the calling subscriber or subscriber station.
In relation to the communication system, method and processing means, it is advantageous for the special services to be selected from the group comprising one or more of the following special services: forwarding a message, advertising or music to the subscriber placing a call; controlling a calculation of fees; performing a bidirectional on-line dialog with the subscriber placing a call; sending information material to the subscriber making a call; limiting the call time; interrupting the call at predetermined intervals of time in order to play advertising/messages or music during the breaks; forwarding bills or application forms to the subscriber making a call; producing statistics; producing itemizations of calls made via the transmission network; controlling the transmission network""s transmission speed for the call to be performed; automatically calling back the subscriber at predetermined intervals of time; and forwarding messages to the subscriber who has been called
Other advantageous embodiments and improvements of the invention are indicated in the dependent claims. The invention will be described in the following by way its embodiments with reference to the drawings. Identical reference numerals and symbols designate identical or similar parts in the drawings.